This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. ELAX is a double blind multicenter randomized trial that tested the effects of Sildenafil with improvement of clinical status in excerise capacity with patients with diastolic heart failure with a normal ejection fraction. this study looks at the benefits of PDE-5 inhibition in patients with pulmonary hypertension. Primay endpoint is the assessment of peak VO2 capacity after 24 weeks.